Suture anchors with locking threads that interlock with adjacent bone tissue

Abstract

Suture anchors having specialized cortical and cancellous bone-engaging segments with optimized thread patterns to enhance mechanical fixation to cortical and cancellous bone. The cortical bone-engaging segment includes fine helical threads and the cancellous bone-engaging segment includes coarse helical locking threads with greater spacing, height, and depth than the fine helical threads. The coarse helical locking threads include one or more of an undercut, concavity, convexity, or protrusion that interlock with adjacent bone to resist lateral movement and tipping and provide greater resistance to pullout. The threaded anchor body includes a central bore, with a socket at a proximal opening and a suture-attachment structure therein. The bore may extend through the cortical bone-engaging segment but not the cancellous bone-engaging segment. This permits the cancellous bone-engaging segment to have a substantially reduced root diameter, which substantially increases the height and depth, and therefore the mechanical bite, of the cancellous bone-engaging threads.

1 . A suture anchor for enhanced engagement with and mechanical fixation to cortical and cancellous bone tissues at a surgical site, comprising:
 an anchor body extending along a longitudinal axis between a proximal end and a distal end;   helical threads on an outer surface of the anchor body and extending at least partially between a proximal face and a distal tip, the helical threads defining a major diameter of the anchor body;   a central bore that opens at the proximal face and includes a socket for receiving a correspondingly-shaped driver tip; and   a rigid member disposed in the central bore and that provides a suture-attachment site;   the anchor body including a cortical bone-engaging segment beginning at the proximal face and extending partially toward the distal tip and a cancellous bone-engaging segment between the cortical bone-engaging segment and the distal tip,   the cortical bone-engaging segment having one or more starts of fine helical threads,   the cancellous bone-engaging segment including coarse helical locking threads, the coarse helical locking threads including one or more of an undercut, concavity, convexity, or protrusion.   
     
     
         2 . The suture anchor of  claim 1 , wherein the cortical bone-engaging segment has a first root diameter and the cancellous bone-engaging segment has a second root diameter less than the first root diameter. 
     
     
         3 . The suture anchor of  claim 1 , wherein the fine helical locking threads have a first thread height and the coarse helical locking threads have a second thread height greater than the first thread height. 
     
     
         4 . The suture anchor of  claim 4 , wherein a ratio of the second thread height to the first thread height is greater than 1.5:1 and less than 3.8:1. 
     
     
         5 . The suture anchor of  claim 1 , wherein at the coarse helical locking threads of the cancellous bone-engaging segment comprise an undercut between a protrusion on an underside of the locking threads and an outer root surface of the anchor body. 
     
     
         6 . The suture anchor of  claim 2 , the coarse helical locking threads further including a concavity formed in a top side of the locking threads. 
     
     
         7 . The suture anchor of  claim 1 , further comprising at least one suture attached to the rigid member. 
     
     
         8 . The suture anchor of  claim 1 , wherein the anchor body comprises a material selected from the group consisting of stainless steel, titanium, nickel-titanium alloy, metal, alloys, and polymers. 
     
     
         9 . The suture anchor of  claim 1 , wherein the rigid member is positioned at a bottom of the central bore proximal to a transition where the cortical bone-engaging segment ends and the cancellous bone-engaging segment begins. 
     
     
         10 . The suture anchor of  claim 1 , wherein the rigid member comprises a transverse pin passing through at least one wall of the anchor body and extending at least partially across the central bore. 
     
     
         11 . The suture anchor of  claim 1 , wherein the rigid member is integrally formed with the anchor body. 
     
     
         12 . The suture anchor of  claim 1 , wherein the socket has a shape selected from hexagonal, pentagonal, square, triangular, star-shaped, oval, or other non-circular or non-cylindrical geometric shape. 
     
     
         13 . A suture anchor system comprising:
 the suture anchor of  claim 1 ; and   a driver comparing a driver tip with a size and shape so as to be received within and mechanically engage the socket of the suture anchor.   
     
     
         14 . The suture anchor system of  claim 13 , wherein the driver includes a hole through which a suture, when attached to the suture anchor, can be threaded. 
     
     
         15 . A suture anchor for enhanced engagement with and mechanical fixation to cortical and cancellous bone tissues at a surgical site, comprising:
 an anchor body extending along a longitudinal axis between a proximal end and a distal end;   helical threads on an outer surface of the anchor body and extending at least partially between a proximal face and a distal tip, the helical threads defining a major diameter of the anchor body;   a central bore that opens at the proximal face and includes a socket for receiving a correspondingly shaped driver tip; and   a rigid member disposed in the central bore and that provides a suture-attachment site;   the anchor body including a cortical bone-engaging segment beginning at the proximal face and extending partially toward the distal tip and a cancellous bone-engaging segment between the cortical bone-engaging segment and the distal tip,   the cortical bone-engaging segment including at least two starts of fine helical threads, the fine helical threads having a thread height defined by a distance between an outer root surface of the anchor body in the cortical bone-engaging segment and outer edges of the fine helical threads,   the cancellous bone-engaging segment including coarse helical locking threads having at least one fewer start than the fine helical threads, the coarse helical locking threads having a thread height defined by a distance between an outer root surface of the anchor body in the cancellous bone-engaging segment and outer edges of the coarse helical threads, the coarse helical locking threads including one or more of an undercut, concavity, convexity, or protrusion,   wherein the central bore extends through the cortical bone-engaging segment but terminates shy of the cancellous bone-engaging segment,   wherein the rigid member is positioned at or near a bottom of the central bore proximal to where the cortical bone-engaging segment ends and the cancellous bone-engaging segment begins,   wherein the cortical bone-engaging segment has a root diameter greater than a root diameter of the cancellous bone-engaging segment,   wherein the thread height of the coarse helical threads is greater than the thread height of the fine helical threads.   
     
     
         16 . The suture anchor of  claim 15 , further comprising at least one tissue-securing suture looped around the rigid member, wherein the at least one tissue-securing suture has free ends exiting the central bore and extending beyond the proximal face. 
     
     
         17 . A suture anchor system comprising:
 the suture anchor of  claim 15 ; and   a driver comparing a driver tip with a size and shape so as to be received within and mechanically engage the socket of the suture anchor.   
     
     
         18 . A suture anchor for enhanced engagement with and mechanical fixation to cortical and cancellous bone tissues at a surgical site, comprising:
 an anchor body extending along a longitudinal axis between a proximal end and a distal end;   one or more starts of helical locking threads on an outer surface of the anchor body and extending at least partially between a proximal face and a distal tip, the helical locking threads defining a major diameter of the anchor body, at least one start of the helical locking threads including one or more of an undercut, concavity, convexity, or protrusion;   a central bore that opens at the proximal face and includes a socket for receiving a correspondingly shaped driver tip; and   a rigid member disposed in the central bore and that provides a suture-attachment site.   
     
     
         19 . The suture anchor of  claim 18 , wherein the anchor body includes a cortical bone-engaging segment with a cortical root diameter and a cancellous bone-engaging segment with a cancellous root diameter, and wherein at least a portion of the cancellous root diameter is equal to the cortical root diameter. 
     
     
         20 . A suture anchor system comprising:
 the suture anchor of  claim 18 ; and   a driver comparing a driver tip with a size and shape so as to be received within and mechanically engage the socket of the suture anchor.